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UC Finds Common Drug Linked to Increased Rate of Brain Hemorrhage

Published February 2007

The rate of intracerebral (brain) hemorrhage associated with blood-thinning drugs quintupled during the 1990s, and in people over 80 the rate increased more than 10-fold, according to a UC study published in the Jan. 9, 2007, issue of the journal Neurology.

The increase in hemorrhage, says UC assistant professor and study author Matthew Flaherty, MD, is due to greater use of the drug warfarin, which is commonly prescribed to prevent blood clotting but carries the side effect of bleeding.

The use of warfarin increased in the 1990s after studies showed it reduced the risk of stroke caused by blood clots in people with atrial fibrillation, a condition that causes irregular heart rhythm and becomes more common as people age. Blood clots can lead to ischemic stroke, the most common type of stroke. An intracerebral hemorrhage is a stroke caused by bleeding in the brain.

For the study, researchers identified all patients in the greater Cincinnati area hospitalized with a first-time intracerebral hemorrhage during three time periods: 1988, 1993 to 1994, and 1999. In 1988, the annual rate of intracerebral hemorrhages associated with use of blood-thinning drugs was 0.8 cases per 100,000 people. In 1999, the rate was 4.4 cases per 100,000 people. For people age 80 and older, the rate increased from 2.5 in 1988 to 45.9 in 1999.

Because warfarin is currently the best way to prevent blood clots in patients with atrial fibrillation, Flaherty cautions that its use should not necessarily be discontinued.

"Warfarin is highly effective in preventing ischemic stroke among people with atrial fibrillation," says Flaherty. "For many, the benefits of preventing ischemic stroke continue to outweigh the risk of a hemorrhagic stroke.

"Our findings should not discourage the use of warfarin when it's appropriate. Doctors can use these findings to make sure they are weighing the risks and benefits of warfarin use for their patients. For researchers, these results may stimulate efforts to develop safer alternatives to warfarin and better treatments for people with brain hemorrhages."

Stroke is the third leading cause of death in the United States. The Centers for Disease Control and Prevention estimates that in the United States about 700,000 strokes occur each year-500,000 being first or new strokes.

The study was supported in part by the National Institute of Neurological Disorders and Stroke.